There is a clinical need to fill and stabilize damaged bones of patients, such as for example, filling defects in collapsed vertebra of patients suffering from severe back pain caused by osteoporosis, metastatic tumors or back injuries. Currently, these defects are repaired using multi-component bone cements that are mixed in open containers, transferred to a device and injected into the damaged bone where the mixture chemically reacts or cures to form a solid support structure.
Most widely used bone cements are based on polymethylmethacrylate (PMMA) and hydroxylapatite. These materials have relatively good strength characteristics, but have a number of drawbacks. These cements are a two-part chemically reactive system and have approximately five to ten minutes of working time once the components are mixed. As for example with the PMMA based system, one of the components is a liquid monomer methylmethacrylate (MMA), which is noxious and toxic to handle. The other component, the polymer component (PMMA), is a powder that can be difficult to mix thoroughly. Moreover, current methods of mixing these two components together are typically done by hand in an open container or dish. This procedure permits significant vaporization of the noxious liquid monomer MMA. Also, the working time increases between mixing and dispensing because once the mixture is mixed it then needs to be transferred to a syringe for injection into the damaged bone. Moreover, the working time is limited because the viscosity of the cement constantly increases during mixing, thus making transferring of the mixture to the syringe and injection of the mixture into the damaged bone more difficult. Often, a very high injection pressure and/or large bore needles may be necessary to inject the mixture, especially if it's near the end of the cement's working life.